Control system and method for regulating valve of low-pressure cylinder of nuclear power unit

Abstract

The present disclosure proposes a control system and method for a low-pressure cylinder regulating valve of a nuclear power unit, which relates to the field of nuclear power technology. The control system comprises: a high-discharge pressure control loop, a disturbance-free switching loop, a trigger, a first switching module, a second switching module, and a rate limiting module. Thus, when switching between the pure condensing condition and the heating condition, the low-pressure cylinder regulating valve can be controlled based on the load control instruction, and the control mode of the low-pressure cylinder regulating valve can be switched between the high-discharge pressure control instruction. The switching process is smooth and no large step disturbance occurs. That is, before and after the switching, the unit load and high-discharge pressure will not fluctuate significantly, thereby avoiding bringing the nuclear power unit into a transient condition, thereby posing a hidden danger to the safe operation of the nuclear power unit.

Description

Technical Field

[0001] The present disclosure relates to the field of nuclear power technology, and in particular to a control system and method for a low-pressure cylinder regulating valve of a nuclear power unit. Background Art

[0002] During normal operation, a nuclear power unit often uses the automatic load control (ALR) method to adjust the load. In this method, the operator sets the load target value and load change rate. During operation, the starting load is increased or decreased to the target load according to the load change rate. The high-pressure cylinder regulating valve GV and the low-pressure cylinder regulating valve ICV of the steam turbine both receive the same load control loop instruction GVPD and control the valve opening according to the valve position instruction converted from their respective valve characteristic curve functions. The controlled variable of the load control loop is the generator power.

[0003] The operating mode of the unit before the heating modification is called pure condensing condition, and the operating mode after the heating modification is called heating condition. The unit load during heating is designed to be in the range of 70% to 100% of the rated load.

[0004] Under purely condensing conditions, the ICV valve remains fully open within the load range of 70% to 100%. The ICV valve has no throttling effect on steam, and unit load control is achieved simply by changing the opening of the GV valve. After the large-scale extraction steam heating retrofit, the heating steam pipeline is connected from the reheat steam cold section. The steam originally used to propel the steam turbine generator is split into two parts: one part is extracted for heating, and the remaining steam is used for power generation. The power output on the nuclear island side remains essentially unchanged. The exhaust pressure of the high-pressure cylinder of the steam turbine (hereinafter referred to as the high-pressure exhaust pressure) gradually decreases with increasing heating steam flow. The pressure differential between the high-pressure final stage and the secondary final stage increases at the same flow rate. If the high-pressure exhaust pressure is not controlled, when the heating steam flow reaches a certain level, the further decrease in the high-pressure exhaust pressure will endanger the safety of the high-pressure blades. To ensure the safety of the high-pressure blades, the high-pressure exhaust pressure must be controlled after the heating retrofit. In addition, when part (all) of the load is suddenly disconnected on the heating system side, it will cause a sharp rise in the high-discharge pressure. In order to prevent the high-discharge pressure from rising to exceed the original cold section system design pressure and causing damage to the original system and equipment, the high-discharge pressure needs to be controlled after the heating transformation. Summary of the Invention

[0005] The present disclosure aims to solve one of the technical problems in the related art at least to a certain extent.

[0006] The first embodiment of the present disclosure provides a control system for a low-pressure cylinder regulating valve of a nuclear power unit, comprising:

[0007] High exhaust pressure control loop, disturbance-free switching loop, trigger, first switching module, second switching module, rate limiting module;

[0008] Wherein, the first input end of the high-pressure exhaust pressure control circuit is connected to the first input end of the disturbance-free switching circuit and the control instruction of the low-pressure cylinder regulating valve at the i-th moment, the second input end is the first deviation between the high-pressure exhaust pressure control target value and the high-pressure measured value, the third input end is the automatic and manual switching instruction, the first output end is connected to the first input end and the second input end of the first switching module, and the second output end is connected to the second input end of the disturbance-free switching circuit;

[0009] The third input end of the disturbance-free switching circuit is the load control instruction of the low-pressure cylinder regulating valve at the i-th moment, and the output end of the disturbance-free switching circuit is connected to the first input end of the trigger;

[0010] The second input end of the trigger is a heat supply exit instruction, and the output end of the trigger is connected to the first input end of the rate limiting module;

[0011] The third input end of the first switching module is the automatic control switching instruction of the low-pressure cylinder regulating valve, and the output end of the first switching module is connected to the first input end of the second switching module;

[0012] The second input end of the second switching module is the load control instruction, the third input end is the heating input instruction, and the output end of the second switching module is connected to the second input end of the rate limiting module;

[0013] The third input end of the rate limiting module is the load control instruction, and the output end of the rate limiting module is the control instruction of the low-pressure cylinder regulating valve at the i+1th moment.

[0014] A second embodiment of the present disclosure provides a control method for a low-pressure cylinder regulating valve of a nuclear power unit, which is applied to a control system of a low-pressure cylinder regulating valve of a nuclear power unit, including:

[0015] When the automatic control switching instruction of the low-pressure cylinder regulating valve inputted by the third input terminal of the first switching module indicates manual control, determining that the input and output of the first switching module are the high-discharge pressure manual control instruction at the i-th moment;

[0016] When the heating input instruction inputted by the third input terminal of the second switching module indicates heating input, determining that the input of the second switching module is switched from the load control instruction to the high discharge pressure manual control instruction outputted by the first switching module;

[0017] The high exhaust pressure manual control instruction is input into the rate limiting module to adjust the opening of the low pressure cylinder regulating valve based on the target rate, and obtain the control instruction of the low pressure cylinder regulating valve at the i+1th time.

[0018] The control system and method for the low-pressure cylinder regulating valve of a nuclear power unit provided by the present disclosure have the following beneficial effects:

[0019] In the disclosed embodiment, a control system for the low-pressure cylinder regulating valve of a nuclear power unit is proposed. When switching between the pure condensing condition and the heating condition, the low-pressure cylinder regulating valve can be adjusted based on the load control instruction, and the control mode of the low-pressure cylinder regulating valve can be switched between the high-discharge pressure control instruction and the low-pressure cylinder regulating valve control mode. The switching process is smooth and no large step disturbance occurs. That is, before and after the switching, the unit load and high-discharge pressure will not fluctuate significantly, thereby avoiding bringing the nuclear power unit into a transient condition, which in turn brings hidden dangers to the safe operation of the nuclear power unit.

[0020] Additional aspects and advantages of the present disclosure will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present disclosure will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0022] Figure 1 A schematic diagram of the structure of a control system for a low-pressure cylinder regulating valve of a nuclear power unit provided by an embodiment of the present disclosure;

[0023] Figure 2 A flow chart of a method for controlling a low-pressure cylinder regulating valve of a nuclear power unit provided by one embodiment of the present disclosure;

[0024] Figure 3 A flow chart of another method for controlling a low-pressure cylinder regulating valve of a nuclear power unit provided by an embodiment of the present disclosure;

[0025] Figure 4 A flow chart of another method for controlling a low-pressure cylinder regulating valve of a nuclear power unit provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0026] The following describes in detail embodiments of the present disclosure, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present disclosure, and should not be construed as limiting the present disclosure.

[0027] The following describes a control system and method for a low-pressure cylinder regulating valve of a nuclear power unit according to an embodiment of the present disclosure with reference to the accompanying drawings.

[0028] Figure 1 This is a structural schematic diagram of the control system of the low-pressure cylinder regulating valve of a nuclear power unit provided by an embodiment of the present disclosure.

[0029] like Figure 1 As shown, the control system of the low-pressure cylinder regulating valve of the nuclear power unit may include: a high-pressure discharge pressure control loop 101, a disturbance-free switching loop 102, a trigger 103, a first switching module 104, a second switching module 105, and a rate limiting module 106;

[0030] Among them, the first input end of the high exhaust pressure control loop 101 is connected to the first input end of the disturbance-free switching loop 102 and the control instruction of the low-pressure cylinder regulating valve at the i-th moment, the second input end is the first deviation between the high exhaust pressure control target value and the high exhaust pressure measurement value, the third input end is the automatic and manual switching instruction, the first output end is connected to the first input end R and the second input end S of the first switching module 104, and the second output end is connected to the second input end of the disturbance-free switching loop 102.

[0031] In some possible implementations, the high exhaust pressure control loop 101 may further include: a first conversion module 1011 , an automatic regulator module 1012 , a manual adjustment module 1013 , and a second conversion module 1014 .

[0032] The first conversion module 1011 has an input terminal that is a control command for the low-pressure cylinder regulating valve at the i-th moment, and an output terminal that is connected to the first input terminal T of the automatic regulator module and the input terminal of the manual adjustment module. The first conversion module 1011 is configured to convert the control command for the low-pressure cylinder regulating valve at the i-th moment into a target opening value for the low-pressure cylinder regulating valve. Specifically, the first conversion module 1011 may convert the control command for the low-pressure cylinder regulating valve at the i-th moment into a target opening value for the low-pressure cylinder regulating valve based on a low-pressure cylinder regulating valve characteristic curve function.

[0033] The second input terminal A of the automatic regulator module 1012 is the automatic and manual switching instruction, the third input terminal S of the automatic regulator module is the first deviation between the high-exhaust pressure target value and the high-exhaust pressure measured value, and the output terminal of the automatic regulator module 1012 is connected to the output terminal of the manual adjustment module, the input terminal of the second conversion module and the second input terminal of the disturbance-free switching loop.

[0034] When the automatic and manual switching instruction indicates automatic adjustment (which can be represented by 1), the input of the automatic adjustment module 1012 is the first deviation between the high-exhaust pressure target value and the high-exhaust pressure measurement value. When the automatic and manual switching instruction indicates manual adjustment (which can be represented by 0), the input of the automatic adjustment module 1012 is the target opening value of the low-pressure cylinder regulating valve output by the first conversion module 1011.

[0035] The output end of the second conversion module 1014 is connected to the first input end and the second input end of the first switching module. The second conversion module is used to convert the data output from the output end of the manual adjustment module into a high-exhaust pressure manual control instruction, and output it to the first input end R of the first switching module; or, convert the data output from the output end of the automatic regulator module into a high-exhaust pressure automatic control instruction, and output it to the second input end S of the first switching module.

[0036] Specifically, the second conversion module 1014 can convert the data output from the output end of the manual adjustment module into a high-exhaust pressure manual control instruction based on the inverse function of the low-pressure cylinder regulating valve characteristic curve function, or convert the data output from the output end of the automatic regulator module into a high-exhaust pressure automatic control instruction.

[0037] For example, if the characteristic curve function of the low-pressure cylinder regulating valve is F1(X), then the inverse function of the characteristic curve function of the low-pressure cylinder regulating valve is F1 -1 (Y).

[0038] The third input terminal of the disturbance-free switching circuit 102 is the load control instruction of the low-pressure cylinder regulating valve at the i-th moment, and the output terminal of the disturbance-free switching circuit 102 is connected to the first input terminal of the trigger.

[0039] In some possible implementations, the bumpless switching circuit 102 may further include: a difference calculation module 1021, an absolute value module 1022, a first judgment module 1023, a second judgment module 1024, and a third judgment module 1025;

[0040] The first input terminal of the difference calculation module 1021 is the first valve opening corresponding to the high-pressure control instruction, the second input terminal is the second valve opening corresponding to the load control instruction, and the output terminal is connected to the input terminal of the absolute value module. The difference calculation module is used to calculate the second deviation between the first valve opening and the second valve opening;

[0041] The output end of the absolute value module 1022 is connected to the input end of the first judgment module 1023, and the absolute value module 1022 is used to calculate the absolute value of the second deviation;

[0042] The output terminal of the first determination module 1023 is connected to the first input terminal of the third determination module 1025. The first determination module is configured to determine whether the absolute value of the second deviation is equal to zero. For example, if the first determination module determines that the absolute value of the second deviation is equal to zero, the output result is 1; otherwise, the output result is 0.

[0043] The input terminal of the second determination module 1024 is connected to the output terminal of the automatic regulator module 1012, and the output terminal is connected to the second input terminal of the third determination module 1025. The second determination module 1024 is used to determine whether the opening of the low-pressure cylinder regulating valve output by the automatic regulator module is fully open. For example, if the second determination module determines that the opening of the low-pressure cylinder regulating valve is fully open, the output result is 1; otherwise, the output result is 0.

[0044] The output terminal of the third judgment module 1025 is connected to the first input terminal R of the trigger 103. The third judgment module can be an OR module, which is used to determine the result of the OR operation between the output result of the first judgment module and the output result of the second judgment module.

[0045] The second input terminal S of the trigger 103 is a heat supply exit instruction, and the output terminal of the trigger 103 is connected to the first input terminal A of the rate limiting module 106;

[0046] Optionally, the trigger logic of the trigger 103 may be as shown in Table 1:

[0047] State 1 State 2 State 3 State 4 The first input terminal R 0 0 1 1 The second input terminal S 0 1 0 1 Output 0 1 0 0

[0048] The first output terminal R being 0 indicates that the output of the third judgment module is 0, that is, the outputs of the first judgment module and the second judgment module are both 0; the first output terminal R being 1 indicates that the output of the third judgment module is 1, and either the output of the first judgment module or the output of the second judgment module is 1, or both are 1. The second output terminal S being 0 indicates that the heating exit instruction indicates that heating has not been exited; the second output terminal S being 1 indicates that the heating exit instruction indicates that heating has been exited.

[0049] The third input terminal A of the first switching module 104 is the automatic control switching instruction of the low-pressure cylinder regulating valve, and the output terminal of the first switching module is connected to the first input terminal S of the second switching module 105; wherein, the automatic control switching instruction is used to indicate whether to automatically control the low-pressure cylinder regulating valve using the high exhaust pressure (which can be represented by 1) or to manually control the low-pressure cylinder regulating valve using the high exhaust pressure (which can be represented by 0).

[0050] The second input terminal R of the second switching module 105 is a load control command, and the third input terminal A is a heating start-up command. The output terminal of the second switching module 105 is connected to the second input terminal T of the rate limiting module. The heating start-up command is used to indicate whether heating is on. If heating is on, the heating start-up command can be 1; if heating is not on, the heating start-up command can be 0. If the heating start-up command indicates that heating is on, the input of the second switching module is determined to be the load control command. If the heating start-up command indicates that heating is not on, the input of the second switching module is determined to be the data output by the output terminal of the first switching module.

[0051] The third input terminal S of the rate limiting module 106 is the load control instruction, and the output terminal of the rate limiting module 106 is the control instruction of the low-pressure cylinder regulating valve at the i+1th moment.

[0052] Optionally, when the first input terminal A of the rate limiting module 106 is 0, the input of the rate limiting module is determined to be the data output by the second switching module. If the first input terminal A is 1, the input of the rate limiting module is determined to be the load control instruction.

[0053] The rate limiting module 106 is further configured to limit the rate of regulating the low-pressure cylinder regulating valve.

[0054] Optionally, the rate limiting module may include an upward rate upper limit value, which means the maximum rate of change of the data input at the second input terminal T or the third input terminal S in the process of changing from a smaller value to a larger value, such as 1% / sec, which means that the maximum upward change of the value is 1% per second.

[0055] Optionally, the rate limiting module may include a downward rate upper limit, which means the maximum rate of change of the data input at the second input terminal T or the third input terminal S during the process of changing from a larger value to a smaller value, such as 1% / sec, which means that the maximum downward change of the value is 1% per second.

[0056] In an embodiment of the present disclosure, a control system for a low-pressure cylinder regulating valve of a nuclear power unit is proposed. When switching between a pure condensing condition and a heating condition, the low-pressure cylinder regulating valve can be adjusted based on a load control instruction, and the low-pressure cylinder regulating valve can be adjusted based on a high-discharge pressure control instruction. The control system switches between the two methods, and ensures smoothness during the switching process without large step disturbances. That is, before and after the switching, the unit load and high-discharge pressure will not fluctuate significantly, thereby avoiding bringing the nuclear power unit into a transient condition, which in turn poses a hidden danger to the safe operation of the nuclear power unit.

[0057] Furthermore, the control system of the low-pressure cylinder regulating valve of the nuclear power unit also designs manual control and automatic control parts in the high-discharge pressure control loop, thereby further ensuring the safe operation of the nuclear power unit.

[0058] Figure 2 This is a flow chart of a method for controlling a low-pressure cylinder regulating valve of a nuclear power unit provided by an embodiment of the present disclosure. The method for controlling a low-pressure cylinder regulating valve of a nuclear power unit is applied to a control system of a low-pressure cylinder regulating valve of a nuclear power unit.

[0059] like Figure 2 As shown, the control method of the low-pressure cylinder regulating valve of the nuclear power unit may include the following steps:

[0060] Step 201 : When the automatic control switching instruction of the low-pressure cylinder regulating valve inputted by the third input terminal of the first switching module indicates manual control, the input and output of the first switching module are determined to be the high exhaust pressure manual control instruction at the i-th moment.

[0061] In this embodiment, a control system based on the low-pressure cylinder regulating valve of a nuclear power unit is shown, which realizes a method of switching between controlling the low-pressure cylinder regulating valve based on load control instructions under pure condensing conditions and controlling the low-pressure cylinder regulating valve based on high exhaust pressure manual control instructions under heating conditions.

[0062] Optionally, you can obtain the high exhaust pressure manual control command by following the steps below:

[0063] (1) First, the load control instruction at the i-th moment is input into the first conversion module, so that the first conversion module converts the load control instruction into the opening of the low-pressure cylinder regulating valve.

[0064] Under purely condensing conditions, the load control command is sent simultaneously to the low-pressure cylinder regulating valve and the high-pressure cylinder regulating valve. The valve openings are then adjusted according to the valve position commands converted from their respective valve characteristic curve functions. Therefore, the load control command at time i must be converted by the first conversion module to obtain the converted low-pressure cylinder regulating valve opening. Specifically, the first conversion module converts the load control command based on the low-pressure cylinder regulating valve characteristic curve function.

[0065] (2) The opening of the low-pressure cylinder regulating valve is input into the manual adjustment module, so as to add the manually adjusted valve opening to the opening of the low-pressure cylinder regulating valve to obtain a first target opening after adjustment.

[0066] The manually adjusted valve opening may be the opening of the low-pressure cylinder regulating valve manually adjusted by a worker.

[0067] (3) The first target opening is input into the second conversion module, so that the second conversion module converts the first target opening into a high exhaust pressure manual control instruction.

[0068] Among them, the second conversion module is based on the inverse function of the low-pressure cylinder regulating valve characteristic curve function, which converts the first target opening into a high-exhaust pressure manual control instruction.

[0069] It should be noted that the first target opening is converted into a high-discharge pressure manual control instruction by the second conversion module because there is a need to switch the high-discharge pressure manually or automatically and to switch from the heating condition back to the pure condensing condition.

[0070] Step 202 : when the heating start-up instruction inputted from the third input terminal of the second switching module indicates heating start-up, it is determined that the input of the second switching module is switched from the load control instruction to the high exhaust pressure manual control instruction outputted by the first switching module.

[0071] Step 203 : Inputting the high exhaust pressure manual control instruction into the rate limiting module to adjust the opening of the low pressure cylinder regulating valve based on the target rate, and obtaining the control instruction of the low pressure cylinder regulating valve at the i+1th moment.

[0072] The rate limiting module 106 is further configured to limit the rate of regulating the low-pressure cylinder regulating valve.

[0073] Optionally, the rate limiting module may include an upward rate upper limit value, which means the maximum rate of change of the data input at the second input terminal T or the third input terminal S in the process of changing from a smaller value to a larger value, such as 1% / sec, which means that the maximum upward change of the value is 1% per second.

[0074] Optionally, the rate limiting module can include a downward rate cap, which represents the maximum rate of change when the data input at the second input terminal T or the third input terminal S changes from a larger value to a smaller value. For example, 1% / sec means the value can change downward by a maximum of 1% per second. It should be noted that manual control offers the advantage of allowing for slow adjustments tailored to the unit's specific conditions. However, the maximum adjustment rate is limited by the rate limiting module.

[0075] In the disclosed embodiment, when the automatic control switching instruction for the low-pressure cylinder regulating valve inputted at the third input terminal of the first switching module indicates manual control, the input and output of the first switching module are determined to be the high-pressure manual control instruction at time i. When the heating start-up instruction inputted at the third input terminal of the second switching module indicates heating start-up, the input of the second switching module is determined to switch from the load control instruction to the high-pressure manual control instruction outputted by the first switching module. Finally, the high-pressure manual control instruction is inputted into the rate limiting module to adjust the opening of the low-pressure cylinder regulating valve based on the target rate, thereby obtaining the control instruction for the low-pressure cylinder regulating valve at time i+1. This achieves switching between controlling the low-pressure cylinder regulating valve based on the load control instruction under pure condensing conditions and controlling the low-pressure cylinder regulating valve based on the high-pressure manual control instruction under heating conditions. Furthermore, the rate limiting module can be used to limit the adjustment rate, thereby avoiding large fluctuations in the unit load and high-pressure before and after switching, which could cause the nuclear power unit to enter a transient operating state and pose a potential risk to the safe operation of the nuclear power unit.

[0076] Figure 3This is a flow chart of another method for controlling a low-pressure cylinder regulating valve of a nuclear power unit provided by an embodiment of the present disclosure. The method for controlling a low-pressure cylinder regulating valve of a nuclear power unit is applied to a control system of a low-pressure cylinder regulating valve of a nuclear power unit.

[0077] like Figure 3 As shown, the control method of the low-pressure cylinder regulating valve of the nuclear power unit may include the following steps:

[0078] Step 301: When the automatic control switching instruction of the low-pressure cylinder regulating valve inputted by the third input terminal of the first switching module indicates manual control, the input and output of the first switching module are determined to be the high exhaust pressure manual control instruction at the i-th moment.

[0079] Step 302 : When the heating start-up instruction inputted from the third input terminal of the second switching module indicates heating start-up, it is determined that the input of the second switching module is switched from the load control instruction to the high exhaust pressure manual control instruction outputted by the first switching module.

[0080] Step 303 : Input the high exhaust pressure manual control instruction into the rate limiting module to adjust the opening of the low pressure cylinder regulating valve based on the target rate, and obtain the control instruction of the low pressure cylinder regulating valve at the i+1th moment.

[0081] In step 304 , when the automatic control switching instruction of the low-pressure cylinder regulating valve inputted from the third input terminal of the first switching module indicates switching from manual control to automatic control, it is determined that the input and output of the first switching module are switched from the high-exhaust pressure manual control instruction to the high-exhaust pressure automatic control instruction.

[0082] The disclosed embodiments not only demonstrate a control system for a nuclear power unit's low-pressure cylinder regulating valve, but also demonstrate a method for switching between controlling the low-pressure cylinder regulating valve based on a load control instruction under purely condensing conditions and controlling the low-pressure cylinder regulating valve based on a high-discharge pressure manual control instruction under heating conditions. Furthermore, after switching to controlling the low-pressure cylinder regulating valve based on a high-discharge pressure manual control instruction, the control of the low-pressure cylinder regulating valve based on a high-discharge pressure manual control instruction can be switched back to controlling the low-pressure cylinder regulating valve based on a high-discharge pressure automatic control instruction.

[0083] Specifically, when the low-pressure cylinder regulating valve is controlled by a manual control instruction based on the high-exhaust pressure, the automatic control switching instruction that controls the low-pressure cylinder regulating valve instructs manual control to switch to automatic control, thereby switching the high-exhaust pressure manual control instruction to a high-exhaust pressure automatic control instruction, and then realizing control of the low-pressure cylinder regulating valve based on the high-exhaust pressure automatic control instruction.

[0084] Optionally, you can obtain the high exhaust pressure automatic control instruction by following the steps below:

[0085] (1) The manual control instruction of the high exhaust pressure before switching is input into the first conversion module, so that the first conversion module converts the manual control instruction of the high exhaust pressure before switching into the opening of the low-pressure cylinder regulating valve.

[0086] (2) inputting the opening of the low-pressure cylinder regulating valve and the first deviation between the high-pressure target value and the high-pressure measured value into the automatic regulator module to obtain a second target opening after automatic control;

[0087] It should be noted that when obtaining the high-pressure automatic control command, the automatic / manual switching command inputted at the second input terminal A of the automatic regulator module is required to indicate automatic control. Furthermore, the input to the automatic regulator module is the first deviation between the high-pressure control target value and the measured high-pressure value. Because the automatic regulator module has a tracking function, it can determine the opening of the low-pressure cylinder regulating valve before the switching.

[0088] (3) The second target opening is input into the second conversion module, so that the second conversion module converts the second target opening into a high exhaust pressure automatic control instruction.

[0089] In some embodiments, after switching to the high-exhaust pressure automatic control instruction to control the low-pressure cylinder regulating valve, if the automatic and manual switching instruction input at the second input terminal A in the control automatic regulator module indicates manual control, the automatic tracking function of the automatic regulator module itself will make its first input terminal T equal to the output terminal value, and the high-exhaust pressure manual control instruction can accept manual increase or decrease adjustment based on the automatic adjustment output.

[0090] In the embodiment of the present disclosure, after the low-pressure cylinder regulating valve is controlled based on the load control instruction under the pure condensing condition and switched to the high-discharge pressure manual control instruction under the heating condition, the input and output of the first switching module can be determined to be switched from the high-discharge pressure manual control instruction to the high-discharge pressure automatic control instruction when the automatic control switching instruction of the low-pressure cylinder regulating valve input at the third input end of the first switching module indicates that the control is switched from manual control to automatic control. In this way, the low-pressure cylinder regulating valve is controlled based on the high-discharge pressure manual control instruction and switched to being controlled by the high-discharge pressure automatic control instruction. The regulation rate can be limited by the rate limiting module, thereby avoiding large fluctuations in the unit load and high-discharge pressure before and after the switching, which would bring the nuclear power unit into a transient condition and thus pose a hidden danger to the safe operation of the nuclear power unit.

[0091] Figure 4 This is a flow chart of another method for controlling a low-pressure cylinder regulating valve of a nuclear power unit provided by an embodiment of the present disclosure. The method for controlling a low-pressure cylinder regulating valve of a nuclear power unit is applied to a control system of a low-pressure cylinder regulating valve of a nuclear power unit.

[0092] like Figure 4 As shown, the control method of the low-pressure cylinder regulating valve of the nuclear power unit may include the following steps:

[0093] Step 401: When the automatic control switching instruction of the low-pressure cylinder regulating valve inputted by the third input terminal of the first switching module indicates automatic control, the input and output of the first switching module are determined to be the high exhaust pressure automatic control instruction at the i-th moment.

[0094] Step 402 : when the heating start-up instruction inputted from the third input terminal of the second switching module indicates heating start-up, the input of the second switching module is determined to be switched from the load control instruction to the high exhaust pressure automatic control instruction outputted by the first switching module.

[0095] Step 403 : Input the high exhaust pressure automatic control instruction into the rate limiting module to adjust the opening of the low pressure cylinder regulating valve based on the target rate, and obtain the control instruction of the low pressure cylinder regulating valve at the i+1th moment.

[0096] As shown in step 401 to step 403, in this embodiment, a control system based on the low-pressure cylinder regulating valve of a nuclear power unit is shown, which realizes a method of switching between controlling the low-pressure cylinder regulating valve based on load control instructions under pure condensing conditions and controlling the low-pressure cylinder regulating valve based on high exhaust pressure automatic control instructions under heating conditions.

[0097] Under high load conditions and low extraction steam for heating, the steam flow rate is relatively unchanged when the low-pressure cylinder regulating valve is near its fully open position, so heating can be achieved by switching directly to automatic high-discharge pressure control. In this case, the low-pressure cylinder regulating valve switches from receiving load control commands under purely condensing conditions to automatic high-discharge pressure control commands under heating conditions.

[0098] If the two control modes are switched directly, due to the different controlled variables (i.e. the controlled variable in pure condensing condition is the unit load, and the controlled variable in heating condition is the high exhaust pressure), in most cases, the low-pressure cylinder regulating valve will convert between the two automatic instruction values ​​at the maximum value of the rate limiter. In this case, disturbance-free switching cannot be achieved.

[0099] Under specific operating conditions, this disclosure designs a bumpless switching circuit for automatically switching the high-discharge pressure back to a purely condensing state to accept the load control command. This specific operating condition occurs when the low-pressure cylinder regulating valve, acting as the actuator in the automatic control circuit, receives a different command due to the difference between the two automatic control commands. Direct switching would result in a step-up or step-down of the automatic control command. This is only possible when the load control command is equal to the high-discharge pressure control command.

[0100] From a process perspective, a common scenario involves a unit operating at rated power for heating. In this scenario, the LP control valve receives a 100% load control command under purely condensing conditions, and the ICV valve actually opens at 100%. Since the heating system has just been commissioned and the pure condensing condition switches to heating, and the extraction steam flow is zero, there's no need for the LP control valve to partially close to compensate for the extraction steam. Therefore, the ICV valve command under the high-discharge pressure automatic control is also 100%, and the actual ICV valve opening is also 100%. Switching between the two control modes under this specific operating condition is non-disruptive.

[0101] In some possible implementations, determining whether a bumpless switch between two adjustment modes is possible may include the following steps:

[0102] (1) The first valve opening corresponding to the high-discharge pressure automatic control instruction after switching and the second valve opening corresponding to the load control instruction before switching are input into the difference calculation module to obtain a second deviation between the first valve opening and the second valve opening.

[0103] (2) Inputting the second deviation into the absolute value module to obtain the absolute value of the second deviation.

[0104] (3) The absolute value of the second deviation is input into the first judgment module to obtain a first judgment result, wherein the first judgment result is used to indicate whether the absolute value of the second deviation is 0.

[0105] (4) The second target opening output by the automatic regulator module is input into the second judgment module to obtain a second judgment result, wherein the second judgment result is used to indicate whether the second target opening is fully open.

[0106] (5) Inputting the first judgment result and the second judgment result into the third judgment module to obtain a target judgment result, wherein the target judgment result is used to indicate whether the load control instruction and the high exhaust pressure automatic control instruction can be switched without disturbance.

[0107] If the absolute value of the second deviation is 0, or the second target opening is fully open, or the absolute value of the second deviation is 0 and the second target opening is fully open, it is determined that the load control instruction and the high exhaust pressure automatic control instruction can be switched without disturbance.

[0108] It should be noted that the low-pressure cylinder regulating valve serves as the high-discharge pressure automatic control circuit under heating conditions. In most cases, the valve is not fully open. Only under very low extraction steam flow rates does it become fully open due to the deadband in the high-discharge pressure automatic control circuit, disengaging from automatic control. However, under purely condensing conditions, the low-pressure cylinder regulating valve receives load control instructions and remains fully open. These two automatic control modes have different regulation targets and controlled quantities, making seamless switching impossible.

[0109] Therefore, the present disclosure designs the values ​​of the rate limiter's "upward rate limit" and "downward rate limit" according to different process conditions. Specifically, in the upward adjustment direction (i.e., when the load control command is increasing the load or the high-discharge pressure automatic control command is moving toward a higher high-discharge pressure setpoint), the maximum value required by the process is used as the rate limit to smooth out the disturbance caused by switching. In the downward adjustment direction (i.e., when the load control command is decreasing the load or the high-discharge pressure automatic control command is moving toward a lower high-discharge pressure setpoint), the unit is adjusted according to its normal maximum adjustment rate.

[0110] Considering the practical need for rapid closure of the low-pressure cylinder regulating valve in abnormal situations such as turbine tripping, the present disclosure is also designed as a straight-through method, without any rate restrictions. In actual heating applications, the heating steam extraction volume is controlled and changes slowly, and the resulting high-pressure set value also changes slowly, without causing large fluctuations.

[0111] In some possible implementations, the target judgment result and the heating exit instruction can also be input into a trigger. If the target judgment result indicates disturbance-free switching and the heating exit instruction indicates heating exit, the instruction input at the first input end of the rate limiting module is determined to be used to instruct the input of the rate limiting module to switch from the load control instruction to the high exhaust pressure control instruction.

[0112] In the disclosed embodiment, when the automatic control switching instruction for the low-pressure cylinder regulating valve inputted at the third input of the first switching module indicates automatic control, the input and output of the first switching module are determined to be the high-pressure discharge pressure automatic control instruction at time i. When the heating start-up instruction inputted at the third input of the second switching module indicates heating start-up, the input of the second switching module is determined to switch from the load control instruction to the high-pressure discharge pressure automatic control instruction outputted by the first switching module. Finally, the high-pressure discharge pressure automatic control instruction is inputted into the rate limiting module to adjust the opening of the low-pressure cylinder regulating valve based on a target rate, thereby obtaining a control instruction for the low-pressure cylinder regulating valve at time i+1. This achieves switching between controlling the low-pressure cylinder regulating valve based on the load control instruction under pure condensing conditions and controlling the low-pressure cylinder regulating valve based on the high-pressure discharge pressure automatic control instruction under heating conditions. Furthermore, the rate limiting module can be used to limit the adjustment rate, thereby avoiding large fluctuations in unit load and high-pressure discharge pressure before and after switching, which could cause the nuclear power unit to enter a transient operating state and pose a potential risk to its safe operation.

[0113] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0114] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the present disclosure, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0115] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present disclosure includes additional implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present disclosure belong.

[0116] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). Furthermore, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing it in another suitable manner if necessary, and then storing it in a computer memory.

[0117] It should be understood that various parts of the present disclosure can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0118] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0119] In addition, the functional units in the various embodiments of the present disclosure may be integrated into a single processing module, or each unit may exist physically separately, or two or more units may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or in the form of software functional modules. If the integrated modules are implemented in the form of software functional modules and sold or used as independent products, they may also be stored in a computer-readable storage medium.

[0120] The storage medium mentioned above may be a read-only memory, a magnetic disk, or an optical disk, etc. Although the embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. A person of ordinary skill in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A control system for a low-pressure cylinder regulating valve of a nuclear power unit, characterized in that: include: High exhaust pressure control loop, disturbance-free switching loop, trigger, first switching module, second switching module, rate limiting module; Wherein, the first input end of the high-pressure exhaust pressure control circuit is connected to the first input end of the disturbance-free switching circuit and the control instruction of the low-pressure cylinder regulating valve at the i-th moment, the second input end is the first deviation between the high-pressure exhaust pressure control target value and the high-pressure measured value, the third input end is the automatic and manual switching instruction, the first output end is connected to the first input end and the second input end of the first switching module, and the second output end is connected to the second input end of the disturbance-free switching circuit; The third input end of the disturbance-free switching circuit is the load control instruction of the low-pressure cylinder regulating valve at the i-th moment, and the output end of the disturbance-free switching circuit is connected to the first input end of the trigger; The second input end of the trigger is a heat supply exit instruction, and the output end of the trigger is connected to the first input end of the rate limiting module; The third input end of the first switching module is the automatic control switching instruction of the low-pressure cylinder regulating valve, and the output end of the first switching module is connected to the first input end of the second switching module; The second input end of the second switching module is the load control instruction, the third input end is the heating input instruction, and the output end of the second switching module is connected to the second input end of the rate limiting module; The third input end of the rate limiting module is the load control instruction, and the output end of the rate limiting module is the control instruction of the low-pressure cylinder regulating valve at the i+1th moment.

2. The control system according to claim 1, characterized in that: The high exhaust pressure control loop includes: a first conversion module, an automatic regulator module, a manual adjustment module, and a second conversion module; The input end of the first conversion module is the control instruction of the low-pressure cylinder regulating valve at the i-th moment, and the output end is connected to the first input end of the automatic regulator module and the input end of the manual adjustment module; the first conversion module is used to convert the control instruction of the low-pressure cylinder regulating valve at the i-th moment into the target opening value of the low-pressure cylinder regulating valve; The second input end of the automatic regulator module is the automatic and manual switching instruction, the third input end of the automatic regulator module is the first deviation between the high-pressure target value and the high-pressure measured value, and the output end of the automatic regulator module is connected to the output end of the manual adjustment module, the input end of the second conversion module, and the second input end of the disturbance-free switching loop; The output end of the second conversion module is connected to the first input end and the second input end of the first switching module. The second conversion module is used to convert the data output from the output end of the manual adjustment module into a high-exhaust pressure manual control instruction, and output it to the first input end of the first switching module; or, convert the data output from the output end of the automatic regulator module into a high-exhaust pressure automatic control instruction, and output it to the second input end of the first switching module.

3. The control system according to claim 2, characterized in that: The disturbance-free switching circuit includes: a difference calculation module, an absolute value module, a first judgment module, a second judgment module, and a third judgment module; The first input terminal of the difference calculation module is the first valve opening corresponding to the high-pressure control instruction, the second input terminal is the second valve opening corresponding to the load control instruction, and the output terminal is connected to the input terminal of the absolute value module, wherein the difference calculation module is used to calculate the second deviation between the first valve opening and the second valve opening; The output end of the absolute value module is connected to the input end of the first judgment module, and the absolute value module is used to calculate the absolute value of the second deviation; The output end of the first judgment module is connected to the first input end of the third judgment module, and the first judgment module is used to judge whether the absolute value of the second deviation is equal to zero; The input end of the second judgment module is connected to the output end of the automatic regulator module, and the output end is connected to the second input end of the third judgment module; The output terminal of the third judgment module is connected to the first input terminal of the trigger.

4. A control method for a low-pressure cylinder regulating valve of a nuclear power unit, applied to the control system according to claim 3, characterized in that: The control system used for low-pressure cylinder regulating valves of nuclear power units includes: When the automatic control switching instruction of the low-pressure cylinder regulating valve inputted by the third input terminal of the first switching module indicates manual control, determining that the input and output of the first switching module are the high-discharge pressure manual control instruction at the i-th moment; When the heating input instruction inputted by the third input terminal of the second switching module indicates heating input, determining that the input of the second switching module is switched from the load control instruction to the high discharge pressure manual control instruction outputted by the first switching module; The high exhaust pressure manual control instruction is input into the rate limiting module to adjust the opening of the low pressure cylinder regulating valve based on the target rate, and obtain the control instruction of the low pressure cylinder regulating valve at the i+1th time.

5. The method according to claim 4, characterized in that Also includes: Inputting the load control instruction at the i-th moment into the first conversion module, so that the first conversion module converts the load control instruction into the opening of the low-pressure cylinder regulating valve; Inputting the opening of the low-pressure cylinder regulating valve into a manual adjustment module, so as to add the manually adjusted valve opening to the opening of the low-pressure cylinder regulating valve to obtain a first target opening after adjustment; The first target opening is input into a second conversion module, so that the second conversion module converts the first target opening into the high exhaust pressure manual control instruction.

6. The method according to claim 4, characterized in that Also includes: When the automatic control switching instruction of the low-pressure cylinder regulating valve inputted by the third input terminal of the first switching module indicates switching from manual control to automatic control, it is determined that the input and output of the first switching module are switched from the high-exhaust pressure manual control instruction to the high-exhaust pressure automatic control instruction.

7. The method according to claim 6, characterized in that Also includes: Inputting the manual control instruction of the high-discharge pressure before switching into the first conversion module, so that the first conversion module converts the manual control instruction of the high-discharge pressure before switching into the opening of the low-pressure cylinder regulating valve; Inputting the opening of the low-pressure cylinder regulating valve and the first deviation between the high-pressure exhaust pressure control target value and the high-pressure exhaust pressure measurement value into the automatic regulator module to obtain a second target opening after automatic adjustment; The second target opening is input into a second conversion module, so that the second conversion module converts the second target opening into the high exhaust pressure automatic control instruction.

8. The method according to claim 4, characterized in that Also includes: When the automatic control switching instruction of the low-pressure cylinder regulating valve inputted by the third input terminal of the first switching module indicates automatic control, determining the input and output of the first switching module as the high-exhaust pressure automatic control instruction at the i-th moment; When the heating input instruction inputted by the third input terminal of the second switching module indicates heating input, determining that the input of the second switching module is switched from the load control instruction to the high discharge pressure automatic control instruction outputted by the first switching module; The high exhaust pressure automatic control instruction is input into the rate limiting module to adjust the opening of the low pressure cylinder regulating valve based on the target rate, and obtain the control instruction of the low pressure cylinder regulating valve at the i+1th time.

9. The method according to claim 8, characterized in that Also includes: Inputting the first valve opening corresponding to the high-discharge pressure automatic control instruction after switching and the second valve opening corresponding to the load control instruction before switching into the difference calculation module to obtain a second deviation between the first valve opening and the second valve opening; inputting the second deviation into an absolute value module to obtain an absolute value of the second deviation; inputting the absolute value of the second deviation into a first judgment module to obtain a first judgment result, wherein the first judgment result is used to indicate whether the absolute value of the second deviation is 0; Inputting the second target opening output by the automatic regulator module into the second judgment module to obtain a second judgment result, wherein the second judgment result is used to indicate whether the second target opening is fully open; The first judgment result and the second judgment result are input into a third judgment module to obtain a target judgment result, wherein the target judgment result is used to indicate whether the load control instruction and the high exhaust pressure automatic control instruction can be switched without disturbance.

10. The method according to claim 9, characterized in that Also includes: Inputting the target determination result and the heating exit instruction into a trigger; If the target judgment result indicates disturbance-free switching and the heating exit instruction indicates that the heating is not exited, the instruction input at the first input end of the rate limiting module is determined to instruct the input of the rate limiting module to switch from the load control instruction to the high exhaust pressure automatic control instruction.

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